The aim of this multicentric prospective study in India was to assess the performance of the QuantiFERON TB-Gold in tube QFT-GIT, Tuberculin Skin Test TST and microbiological results as additional tools for diagnosing active tuberculosis TB and latent infection LTBI according to Human Immunodeficiency Virus HIV status.

Methods

Individuals with and without active TB and HIV infection were enrolled between 2006–2008. QFT-GIT and TST results were analyzed per se and in combination with microbiological data.

Results

Among the 276 individuals 96 active pulmonary TB and 180 no active TB tested by QFT-GIT, 18 indeterminate results 6.5% were found, more significantly numerous in the HIV-infected 15-92; 16.3% than the HIV-uninfected 3-184; 1.6%p<0.0001. QFT-GIT sensitivity for active TB was 82.3% and 92.9% respectively after including or excluding indeterminate results. Clinical sensitivity was significantly lower in the HIV-infected 68.4% than the HIV-uninfected 91.4% patients p = 0.0059. LTBI was detected in 49.3% of subjects without active TB but varied according to TB exposure. When the TST and QFT-GIT were concomitantly performed, the respective sensitivity for active TB diagnosis was 95.0% and 85.0% in the HIV-uninfected p = 0.60, and 66.7% and 51.5% in the HIV-infected patients p = 0.32. QFT-GIT and TST respective specificity for active TB in the HIV-uninfected was 25.0% and 57.1% p = 0.028, and 64.8% and 83.3% in the HIV-infected p = 0.047. In those with active TB, QFT-GIT results were not associated with microbiological parameters smear grade, liquid culture status, time-to-positivity of culture or clinical suspicion of active TB score provided by the clinicians at enrollment. Combining microbiological tests with both immunological tests significantly increased sensitivity for active TB diagnosis p = 0.0002, especially in the HIV-infected individuals p = 0.0016.

Conclusion

QFT-GIT and TST have similar diagnostic value for active TB diagnosis. In HIV-infected patients, combining microbiological tests with both immunological tests significantly increases the sensitivity for active TB diagnosis.